brew uninstall --zap: removing the files a Homebrew app leaves in your Library, and the catch

brew uninstall --cask some-app removes the app from Applications. It does not touch what the app created in your Library: caches, preferences, application support data, logs. That is the same gap as dragging an app to the Trash. Homebrew has an option that closes it.

What zap does

Many casks include a list of the files and folders the app creates, written by whoever maintains that cask. --zap removes them along with the app.

brew uninstall --zap --cask some-app

See the list before you run it

brew cat --cask some-app | sed -n '/zap/,/^  end/p'

That prints the cask's zap section: the paths it will move to the Trash or delete. Read it. Some casks list folders shared by every app from the same company.

Apps you already uninstalled

Zap only works on an installed cask. For an app removed months ago, read its zap list with brew cat (it works without installing) and remove what you find by hand, moving to the Trash so you can undo it.

brew cat --cask some-app | grep -E '~/Library|/Library' | tr -d '",' 

The rest of Homebrew's leftovers

brew autoremove          # dependencies nothing needs any more
brew cleanup --prune=all # old versions and the download cache

Our guides to Homebrew's cache and Homebrew packages cover both in more depth.